Rockwell hardness

This test method is used to determine the hardness of a test specimen as a function of the depth of indentation, taking the elastic recovery into consideration.

A steel ball with a defined applied load is pressed onto a test specimen and the load is then released again. Only the plastic deformation is observed. There are various Rockwell hardness scales which differ according to the combination of indenter and applied load.


Rockwell hardness scaleIndenter diameter [mm]Applied load [N]
R 12,7 588,4
L 6,35 588,4
M 6,35 980,7
Results of the test method
  • The Rockwell hardness is expressed as a number prefixed by the scale letter (R, L, M).